Heating device



Oct. 2, 1956 3. W555 I 2,764,969

HEATING DEVICE Filed March 30, 1953 FIG. 3

INVENTOR GERHAFZT WEJSS BYWOeKrW ATTORNEYS HEATING DEVICE Gerhart Weiss, Forest Hills, N. Y.

Application March 30, 1953, Serial No. 345,355

4 Claims. (Cl. 126-208) This invention relates to an improved catalytic heating system.

One important object of my invention is to provide an improved heating system of the type comprising a plurality of tubes through which an air-fuel mixture'may be forced and containing a catalytic charge for flameless combustion of the air-fuel mixture.

Without limitation thereto, one application of my invention is the provision of a suit incorporating such heating tubes for use by human beings under low temperature conditions. Said heating tubes are also suitable for use in both fixed and portable industrial installations.

Each heating tube comprises a flexible outer tube which has an open inlet end for reception of the fuel-air mixture and a closed outlet end. Said tube surrounds an inner tube comprising flexible tube sections alternating with rigid metal tube sections. The inlet end of the inner tube is closed, and the outer end of the inner tube is open to permit the escape of exhaust gases.

Each rigid tube section includes an axially extending reaction tube of reduced diameter and ducts leading from the reaction tube to the space between the inner tube and the outer tube. Each rigid tube section includes further ducts for communication between the preceding aind succeeding flexible tube sections.

Each reaction tube contains a suitable catalytic charge. Air-fuel mixture passes from the space between the inner tube and the outer tube into the various reaction tubes, where the fuel undergoes flameless combustion with a resulting liberation of heat. The exhaust gases of the reaction tubes pass through the flexible tube sections and through the ducts connecting same and thence out of the outlet end of the inner tube.

I have found it possible to construct heater tubes of the above-described type which give off heat substantially uniformly over the entire length thereof. Ice formation on the catalytic charges is minimized by my construction. Once the reaction is started at the inlet end of a heater tube, the heat given off tends to warm the air-fuel mixture and also succeeding reaction tubes, whereby to facili tate combustion throughout the tube. Optionally, the air-fuel mixture may be externally pre-heated before on tering the heater tube.

Other objects and advantages of my invention will become apparent from the following description, in conjunction with the annexed drawings, in which preferred embodiments are disclosed.

in the drawings,

Fig. 1 is an exploded perspective view showing a segment of a reaction tube, through which an air-fuel mixture may be forced, and also showing four carriers for catalysts which may be mounted in the alternative within said tube for causing combustion of a portion of said air-fuel mixture.

Fig. 2 is a diagrammatic view showing a suit having heater tubes in accordance with my invention.

Fig. 3 is a longitudinal section, partly in elevation, showing a detail of the heater tube shown in Fig. 4.

States Patent Fig. 4 is a longitudinal section, partly in elevation, of a heater tube in accordance with my invention.

Fig. 2 shows one application of the invention, in which tube 49 is connected to a series of heater tubes 70 in a suit 71, said suit 71 being suitable for hum-an wear. Said tube 49 is connected to the junction of a spine tube 70a and a pair of leg tubes 70b. Suitable rib tubes 70c and arm tubes 70d branch off from tube 700. Each of the tubes 70a, 70b, 70c and 70d is open at its outer end. A mixture of air or oxygen and a selected gaseous fuel may be forced through tube 49, in the direction of arrow 61, by any suitable means (not shown). Some of the air-fuel mixture from tube 49 passes through each of the tubes 70. Some or all of the mixture in each of the tubes 70 undergoes combustion, and exhaust gases leave the tubes 70 at their open ends. For example, exhaust gases leave tube 20a in the direction of arrow 72.

The distribution of tubes 70 results in the even heating of suit '71. Optionally, tubes 70 may be arranged in other ways for other heating purposes.

Fig. 4 shows a section of tubing which is particularly suitable for use as one of the tubes 70, or a portion thereof. Fig. 3 shows a detail of Fig. 4.

Figs. 3 and 4 show a longitudinal outer tube 1 which is preferably flexible and gas-impervious. Tube 1 may be made of rubber or a suitable plastic. Tube 1 is open at both of its ends. The inlet end of tube 1 is its left end, as taken in Figs. 3 and 4.

Within tube 1, there is located an inner tube comprising sections of tubing 2. alternating with'sections of rigid tubing 5, 6. Preferably, each tube section 2 is made of metal with an undulatory peripheral wall, as clearly shown in Figs. 3 and 4, in order that it may be somewhat flexible and also have considerable structural strength.

The inlet section of the inner tube is a tube section 2, and the inlet end of said inlet tube section 2 is sealed by any suitable plug 4.

Each rigid tube section comprises a male tube section 5 and a female tube section 6, both of which are preferably made of metal. Said tube section 5 is substantially cylindrical and solid and has respective coaxial, cylindrical end extensions 5a and 5b of reduced diameter. Said tube extension 5a is hollow and is adapted to fit frictionally within the outlet end of the bore of a tube section with said tube section 2 abutting tube 5. Said tube extension 5b is solid and its peripheral wall is screw-threaded.

Said tube section 6 is hollow and its peripheral wall is internally screw-threaded at the inlet end thereof. Tube section 6 and tube section 5 may be secured together by screwing tube extension 5b into the threaded end of tube section 6 until tube section 6 and tube section 5 abut each other.

The outlet end of tube section 6 is provided with an integral, hollow, cylindrical, male extension 6a of reduced diameter, which is adapted to fit frictionally within the inlet end of the bore of a tube section 2, with said tube section 2 abutting tube section 6.

Preferably, the external peripheral faces of said tube sections 2 and said tube sections 5, 6 have substantially the same external diameter, with the outer peripheral faces of tubes 2 having circumferential grooves as a result of the undulatory construction thereof. As a result, a substantially annular space or duct if is provided between the inner peripheral wall of tube 1 and the outer peripheral wall of the tube sections 2, 5 and 6 when the axes of said tube sections 2, 5 and 6 are substantially alined with the axis of tube 1. However, as will be apparent from the following description, such axial alinement is not necessary, and it is only necessary to secure the inner tube to tube 1 at the outlet end of the tubes.

As is shown in Fig. 4, the outlet end of duct 11 is blocked by a substantially annular and gas-tight plug 3.

Said plug 3 fits frictionally within the bore of tube 1 at the outlet end thereof. The tube section 2 at the outlet end of the inner tube extends frictionally through the opening of plug 3. i V

A hollow, cylindrical reaction tube 8 is positioned within each tube section 6, in axial alinement therewith. The diameter of tube 8 is substantially less than the diameter of tube section 6. Tube 8 is open at both of its ends. The outlet end of tube 8 is preferably slightly spaced axially from the outlet end of tube section 6. The inlet end portion of tube 8 extends frictionally into a suitable cylindrical recess in tube extension 5b and optionally extends slightly into tube section 5.

Tube section 5 has a peripheral groove 7. A plurality of radial ducts 7a extend inwardly in tube section 5 from groove 7 and communicate with an axial duct 71') in said tube section 5. Said duct 7b in turn communicates with the bore of reaction tube 8.

A plurality of through-and-through ducts are formed in tube section 5 and tube section 5b, the axes of said ducts 10 being parallel to the axis of tube section 5. Said ducts 10 are located radially outwardly of tube 8. Said ducts 10 extend between the inner space of tube extension 5a and the inner space of tube section 6.

Tube 3 preferably contains a catalytic charge 9 for flamcless combustion of the air-fuel mixture Within said tube 8. Optionally, said charge 9 may comprise a plurality of small platinum granules, as shown in Figs. 3 and 4. Other catalysts may be used, and other internal constructions of tube 8 for reception of the catalyst may be used.

Modifications of reactor tube 8 are shown in Fig. 1, which shows tube 8 in exploded view with a number of alternative charges. Numeral 9c designates a perforated disc for insertion in tube 8, said disc 9c being coated on all of its surfaces with a catalyst. Numeral 9b designates a wire mesh for insertion in tube 8, said mesh 9b being coated on all of its surfaces with a catalyst. Numberal 9a designates a mass 9a of steel wool or other metal wool, or of other fibrous, heat-resistant material, which may be impregnated with catalyst and inserted in tube 8. Numeral 8c designates a plurality of concentric tubes held mechanically in co-axial relationship, which may be coated with catalyst and inserted within tube 8 or substituted for tube 8.

The operation of the heating tube is as follows:

A selected air-fuel mixture enters the inlet end of tube 1, under pressure in excess of atmospheric pressure, in the direction of arrows 12, and enters duct 11. It will be apparent that the circumferential distribution of the air-fuel mixture within duct 11 will tend to be fairly even and will tend to maintain the inner tube axially alined with outer tube l. The air-fuel mixture flows through duct 11 in the direction of arrows 16.

At each of the grooves 7, a portion of the air-fuel mixture enters the ducts 7a associated therewith in the direction of arrow 13, and flows into duct 8 (arrow 14). The air-fuel mixture flows through duct 8 in contact with the catalytic charge 9 and undergoes substantially complete flameless combustion therein, liberating heat. The exhaust gases of the reaction in tube 8 leave said tube 8, in the direction of arrows 15; flow through the succeeding tube section 2, in the direction of arrows 17; how through the succeeding tube extension 5a, in the direction of arrows 13; flow through ducts lit, in the direction of arrow of arrow 19; and flow through the succeeding tube 6 in the direction of arrows 19a.

it will be apparent, therefore, that the exhaust gases of each reaction tube 8 have a clear flow path through the inner tube and finally leave the outlet tube section 2 in the direction of arrows 12a. On the other hand, the outlet end of duct 11 is closed by plug 3, thereby making it certain that the air-fuel mixture will not be wasted and that air-fuel mixture will enter all of the reaction tubes 8 in fairly even amounts as long as the inlet pressure is maintained.

Example The internal diameter of tube 8 was approximately 0.040 inch. The particles of catalytic charge 9 were of approximately 24 to 29 mesh size. The external diameter of tube 1 was approximately A; inch. The difference between the external diameter of tube 8 and the internal diameter of tube 6 was approximately inch. The difference between the external diameter of tube 6 and the internal diameter of tube 1 was approximately A inch. The distance between successive tubes 8 was approximately 3-3 /2 inches. The length of each tube 8 was approximately 78 inch.

In the example, it was found that reaction temperatures in the reaction tubes 8 were high, as the result of the central axial location of said tubes 8. This led to greater efficiency in reacting the fuel-air mixture. It Was found that after the reaction started, the air-fuel mixture entering duct 11 was pro-heated by contact with the metal tube sections 5 and 6 before entering the various reaction tubes 8, thereby further increasing the reaction efiiciency.

It was believed that most of the heat given oil by the heater tube was the result of heat radiation from the reaction tubes 8. This radiated heat was to a considerable extent dilfused over the lengths of tube between the reaction tubes 8 as a result of conduction along the metal tube sections 2, 5 and 6 and as a result of gas convection currents in duct 11.

It was found readily possible to obtain stable steady state operation of the heater tube with a substantially uniform outer surface temperature of tube 1 of approximately 43 C.

At very low external temperatures, such as 40 C., it was found preferable to supply a thermal impulse to the air-fuel mixture at the start of the heating operation. Once one of the tubes 8 started a reaction, it was found that the generated heat caused the remaining tubes 8 to start their reactions successively. Optionally, the air was preheated throughout the heating operation.

Optionally, the heater can utilize a counter flow principle by having the fuel-gas mixture enter duct 11 at the right end thereof, as taken in Fig. 4, and flow from right to left. Plug 3 is then shifted to the other end of the tube. This facilitates pre-heating of the fuel-gas mixture prior to its entrance into tubes 8.

In the example, a mixture of di-methyl-ether and methyl alcohol droplets, together with air, was forced through tube 19. Other suitable fuels can optionally be substituted.

While I have disclosed a preferred embodiment of my invention and have indicated various changes, omissions and additions which may be made therein, it will be apparent that various other changes, omissions and additions may be made in my invention without departing from the scope and spirit thereof.

What is claimed is:

l. A heater for combustion of a vaporized fuel-air mixture and the like, comprising a longitudinal outer tube having an open inlet end for reception of said airfuel mixture, a longitudinal inner tube within said outer tube, a plurality of reaction tubes, means carried by said inner tube for respectively supporting said reaction tubes within said inner tube, said reaction tubes extending longitudinally and being longitudinally spaced and being of smaller diameter than the bore of said inner tube, and ducts within said inner tube respectively communicating with the space between said inner tube and said outer tube and with the respective inlet ends of said reaction tubes for passage of said air-fuel mixture to said reaction tubes, said reaction tubes respectively containing catalytic charges for reaction of the gas-fuel mixture therein, said supporting means respectively having longitudinal through-and-through passages for flow of the gaseous exhaust products of said reaction tubes to the outlet end of said inner tube, said outlet end of said inner tube being open.

2. A heater for combustion of a vaporized fuel-air mixture and the like, comprising a longitudinal outer tube, a longitudinal inner tube within said outer tube, the space between the peripheral Walls of said tubes being adapted to receive said air-fuel mixture, a plurality of reaction tubes, means carried within said inner tube for respectively supporting said reaction tubes so that they extend longitudinally and are longitudinally spaced, and ducts Within said inner tube respectively communicating with the space containing said air-fuel mixture and with the respective inlet ends of said reaction tubes for passage of said air-fuel mixture to said reaction tubes, said reaction tubes respectively containing catalytic charges for the reaction of the gas-fuel mixture therein, said supporting means respectively having longitudinal through-andthrough passages for flow of the gaseous exhaust products of said reaction tubes from the respective outlet ends thereof through said inner tube.

3. A heater for combustion of a vaporized fuel-air mixture and the like, said heater comprising a longitudinal outer tube having an open inlet end for reception of said fuel-air mixture, and a longitudinal inner tube within said outer tube, said inner tube comprising hollow tube sections and connecting tube sections in alternation, each said connecting tube section comprising a male tube member and a female tube member, said male tube member having a main portion, a hollow inlet extension for gastight reception Within the outlet end of a hollow tube section, and a solid outlet extension, each said female tube member being hollow and having an inlet end for gastight reception of said tube outlet extension and an outlet end portion for gas-tight reception within the inlet end of a hollow tube section, hollow, open-ended reaction tubes, each said tube outlet extension having an axial outlet opening for reception of a respective reaction tube in co-axial relation therewith, a catalytic charge in each reaction tube for reaction of the gas-fuel mixture therein, conduit means within each said male tube member between the outer peripheral surface thereof and the inlet end of said reaction tube for passage of gas-fuel mixture to said reaction tube, and through-and-through conduit means in each said male tube member between the inlet end of the main portion thereof and the outlet end of the outlet extension thereof for permitting flow of the gaseous exhaust products of said reaction tubes within said inner tube to the outlet end thereof, the outlet end of said inner tube being open.

4. A heater for combustion of a vaporized fuel-air mixture and the like, comprising a longitudinal outer tube, a longitudinal inner tube Within said outer tube, one of the inner spaces of said inner tube and the space between the peripheral Walls of said tubes being adapted to receive said air-fuel mixture, a plurality of reaction tubes, means carried Within said inner tube for respectively supporting said reaction tubes so that they extend longitudinally and are longitudinally spaced, and passages Within said inner tube respectively communicating with the space containing said air-fuel mixture and with the respective inlet ends of said reaction tubes for passage of said air-fuel mixture to said reaction tubes, said reaction tubes respectively containing catalytic charges for the reaction of the gasfuel mixture therein, said reaction tubes respectively having outlets communicating with the other of said spaces, for flow of the gaseous exhaust products of said reaction tubes through said other space, said supporting means respectively having longitudinal through-and-through passages for continuous gas flow through said inner space of said inner tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,042,690 Weber June 2, 1936 2,357,174 Curtis Aug. 29, 1944 2,384,852 Schmitt Sept. 18, 1945 2,409,965 Udale Oct. 22, 1946 2,493,266 Schmitt Jan. 3, 1950 

